Operations in which wood or other material is shaped, drilled or cut by a power tool require the cutting edge of the tool and the workpiece to be precisely positioned relative to each other in order to achieve the desired results. For example, when a piece of wood is being cut by a table saw, the operator typically feeds the wood piece by hand through the saw blade along the axis of the desired cut to achieve as straight a cut as possible. This normally requires the aid of a "fence" or other alignment tool, which is oriented along the desired cut axis. The fence helps guide the wood piece through the saw blade when the fence is positioned at a desired spacing distance from the saw blade.
Other woodworking operations require marking of reference lines and scribe marks on a workpiece at a predetermined distance from a reference edge or reference mark. Other set-up operations require setting of the depth of cut of a cutting tool such as a saw blade or router bit relative to the support surface of a table or other workpiece support.